Prepatellar bursitis

Introduction and Overview

Prepatellar bursitis is inflammation of the prepatellar bursa, a small fluid-filled sac overlying the anterior patella. It is one of the most common forms of bursitis encountered in primary care, presenting as a discrete swelling over the kneecap. Colloquially known as “housemaid’s knee,” it is prevalent in occupations requiring prolonged kneeling, including carpet laying, gardening, plumbing, and cleaning.

In Australia, prepatellar bursitis is managed predominantly in general practice and is highly amenable to conservative treatment. The critical clinical priority is distinguishing between septic (infectious) and non-septic (aseptic) bursitis, as septic bursitis requires urgent antibiotic therapy and sometimes surgical drainage. Approximately 10–20% of prepatellar bursitis cases are septic, most commonly caused by Staphylococcus aureus.

This guideline covers the Australian primary care approach to diagnosis, aspiration, management, and follow-up of prepatellar bursitis, including specific considerations for occupational health, antibiotic selection, and prevention of recurrence.

Pathophysiology

The prepatellar bursa is a superficial bursa located between the skin and the anterior patella. Its physiological role is to reduce friction and facilitate gliding of the skin over the patella during knee flexion. Inflammation occurs through two principal mechanisms: mechanical and infective.

Non-septic (aseptic) bursitis results from repeated mechanical trauma or sustained pressure over the bursa. Microtrauma from kneeling triggers an inflammatory cascade involving prostaglandins, cytokines (IL-1β, TNF-α), and increased bursal fluid production. Acute trauma (direct blow) may cause haemobursitis — haemorrhagic fluid accumulation. Chronic inflammatory bursitis may develop bursal wall thickening and fibrous adhesions over time. Crystal deposition (uric acid in gout, calcium pyrophosphate) can precipitate acute inflammatory bursitis indistinguishable from septic bursitis without aspiration.

Septic bursitis most commonly results from direct inoculation through a skin breach overlying the bursa — a minor abrasion, laceration, or puncture wound may be sufficient. Haematogenous seeding is less common. Staphylococcus aureus accounts for approximately 80% of cases, with group A Streptococcus and gram-negative organisms seen in immunocompromised patients. The superficial location and poor vascular supply of the bursa predispose to bacterial proliferation and abscess formation. Untreated septic bursitis may progress to cellulitis, osteomyelitis, or septic arthritis.

Clinical Presentation

Prepatellar bursitis presents as swelling over the anterior knee, localised to the patella. The key clinical task is differentiating non-septic from septic bursitis, and bursitis from septic arthritis (which affects the joint space and is a medical emergency).

⚠ Red flags requiring urgent assessment: fever or rigors with knee swelling; rapid enlargement of swelling over 24–48 hours; marked erythema extending beyond the bursa; suspected septic arthritis (joint-line tenderness, restricted ROM, joint effusion); skin breach over the bursa; diabetes or immunocompromise with any hot swelling; failure to improve with conservative management after 5–7 days.

Non-septic Bursitis

Gradual onset (days to weeks); soft fluctuant swelling anterior to patella; mild warmth; no or low-grade fever; pain with direct pressure and kneeling; knee ROM preserved; systemically well; occupational or hobby kneeling trigger typically identified.

Septic Bursitis

Rapid onset (hours to days); hot, tender, erythematous swelling; high fever (>38°C); severe pain; skin breach may be evident; patient systemically unwell; cellulitis may extend from bursa; lymphangitis in severe cases.

Crystal Bursitis (Gout/CPPD)

Acute onset; intensely inflamed bursa; may mimic septic bursitis clinically; hyperuricaemia in gout; associated tophi; prior gout history. Cannot be diagnosed clinically — exclude septic bursitis by aspiration and crystal analysis.

Haemobursitis

Follows acute direct trauma to anterior knee; painful, tense, fluctuant swelling; ecchymosis may be present; aspiration reveals bloody fluid; usually resolves with conservative management and compressive bandaging.

Distinguishing bursitis from septic arthritis: In prepatellar bursitis, the swelling is localised anterior to the patella and external to the joint space. Knee ROM is usually preserved (limited only by pain). In septic arthritis, the joint is globally swollen with intra-articular effusion, ROM is severely restricted, and the patient is typically more systemically unwell. If doubt exists, aspirate the joint separately and urgently.

Investigations

Bursal aspiration is the cornerstone investigation in prepatellar bursitis. It provides diagnostic fluid analysis and therapeutic benefit through decompression. All cases with diagnostic uncertainty, significant swelling, or any features of septic bursitis should undergo aspiration.

Aspirate before treating with antibiotics where possible. Culture-guided therapy reduces broad-spectrum antibiotic use. Gram stain positivity supports septic bursitis but a negative result does not exclude infection. Do not delay starting antibiotics if the patient is systemically unwell.

Bursal aspiration

Sterile technique; 18–20G needle; approach from lateral or medial aspect. Send for: WBC and differential, MC&S, Gram stain, crystal analysis, glucose and protein. WBC >2,000/μL with neutrophil predominance suggests infection; >50,000/μL strongly suggests septic bursitis.

Blood tests

If septic bursitis suspected: FBC (leukocytosis), CRP/ESR (elevated in septic bursitis), blood cultures if febrile, serum uric acid if gout suspected. Normal inflammatory markers do not exclude early or mild septic bursitis.

Imaging

Usually not required. Ultrasound: confirms bursal fluid, guides aspiration, identifies abscess or bursal wall thickening. MRI: if septic arthritis or osteomyelitis suspected. X-ray: limited utility; may show soft tissue swelling; useful to exclude fracture if trauma history.

Bursal fluid analysis

Non-septic: clear/straw-coloured, WBC <2,000/μL, culture negative. Septic: turbid/purulent, WBC >10,000–50,000/μL neutrophil predominant, culture positive. Crystal: WBC variable, monosodium urate needles (gout) or rhomboid CPPD crystals on polarised microscopy.

Severity Assessment

Severity assessment determines the urgency of management. The primary differentiation is septic versus non-septic bursitis. Within non-septic bursitis, severity guides aspiration, injection, and physiotherapy decisions.

Mild Non-septic Bursitis

Small effusion; mild pain (NRS 1–4); minimal functional limitation; no systemic features; long-standing or recurrent; occupational trigger identified. Management: activity modification, knee padding, NSAIDs or paracetamol PRN, ice and compression. Review in 2–4 weeks. Aspiration not always required if mild and clearly non-septic.

Moderate Non-septic Bursitis

Moderate-to-large effusion; moderate pain (NRS 4–7); functional limitation affecting work or daily activities; no septic features; significant impact on occupation. Aspirate (diagnostic + therapeutic); consider corticosteroid injection after culture confirmed negative; physiotherapy; activity restriction; NSAIDs. Review 1–2 weeks.

Septic Bursitis

Any fever, hot swelling, rapid onset, skin breach, or systemic unwellness. Urgent: aspirate immediately; send for MC&S; commence empirical antibiotics without delay. Consider hospital admission if severe, systemically unwell, immunocompromised, or failure of oral antibiotics at 48–72 hour review. Surgical drainage if abscess or antibiotic failure.

General Treatment Principles

Management of prepatellar bursitis depends on aetiology (septic vs. non-septic), severity, and patient factors. Non-septic bursitis is managed conservatively with aspiration, activity modification, and analgesia. Septic bursitis requires antibiotics and repeated aspiration or surgical drainage.

Activity modification and knee protection: Avoid kneeling and direct pressure on the bursa. Use knee pads for work-related tasks. Relative rest from provocative activities during the acute phase. For workers who cannot avoid kneeling, consider WorkCover referral and modified duties documentation.
Aspiration: First-line therapeutic intervention for moderate-to-large bursitis. Removes inflammatory fluid, reduces pain and pressure, and provides diagnostic material. May need to be repeated if fluid reaccumulates. Apply compressive bandage after aspiration to reduce reaccumulation.
Ice and compression: Apply ice packs (wrapped in cloth) for 15–20 minutes several times daily to reduce inflammation. Compressive bandaging after aspiration reduces re-accumulation. Elevate the limb where possible during the acute phase.
Analgesia: Paracetamol or NSAIDs (if not contraindicated) for pain relief. Topical NSAIDs useful for superficial bursitis in elderly or those at GI/renal risk. Avoid opioids for non-septic bursitis.
Corticosteroid injection: Consider after aspiration and culture negativity is confirmed in non-septic inflammatory bursitis. Do not inject if any possibility of septic bursitis — corticosteroids will worsen infection.
Surgical referral: Required for confirmed septic bursitis failing antibiotic therapy, bursal abscess, or recurrent chronic non-septic bursitis failing conservative management. Bursectomy is definitive for persistent or recurrent disease.

Directed Pharmacotherapy

Pharmacotherapy in prepatellar bursitis is targeted to the underlying aetiology. Non-septic bursitis requires analgesia and anti-inflammatory therapy; septic bursitis requires antibiotics. Never use corticosteroid injection without confirming culture negativity from aspirated bursal fluid.

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NSAIDs (Naproxen, Ibuprofen, Diclofenac)

Naprosyn®, Nurofen®, Voltaren® | Non-septic bursitis — anti-inflammatory and analgesia

DOSE Naproxen 500 mg BD orally with food; Ibuprofen 400–600 mg TDS with food; Diclofenac 50 mg BD–TDS; or topical Diclofenac 1% gel QID applied to bursa

PBS STATUS ✓ PBS: General benefit (oral NSAIDs); Not PBS-listed (topical — OTC available)

NOTES Effective for pain and inflammation in non-septic bursitis. Use lowest effective dose for shortest duration. Add PPI for GI protection if oral NSAID used >2 weeks. Avoid in renal impairment, cardiovascular disease, or high GI risk. Topical diclofenac preferred in elderly or those with GI or renal risk.

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Paracetamol

Panadol® and generics | Mild non-septic bursitis — baseline analgesia

DOSE 500–1000 mg orally every 4–6 hours as needed; maximum 4 g/day

PBS STATUS ✓ PBS: General benefit

NOTES First-line analgesic for mild pain. Less anti-inflammatory efficacy than NSAIDs but preferred when NSAIDs are contraindicated. Use regularly for 1–2 weeks to assess benefit. Reduce dose to 2 g/day in hepatic impairment or heavy alcohol use.

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Corticosteroid injection (non-septic, culture-negative only)

Methylprednisolone acetate (Depo-Medrol®) or Triamcinolone acetonide | Non-septic inflammatory bursitis — ONLY after culture confirmed negative

DOSE Methylprednisolone acetate 40 mg intrabursal; or Triamcinolone 20–40 mg intrabursal; apply compressive bandage post-procedure

PBS STATUS PBS: Not PBS-listed (technique fee claimable)

NOTES ONLY after aspiration confirms culture-negative fluid. CONTRAINDICATED if any suspicion of septic bursitis — will worsen infection. Limit to 1–2 injections per episode. Post-injection compression reduces reaccumulation. Effective for gout-related or non-septic inflammatory bursitis.

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Dicloxacillin (oral) — septic bursitis first-line

Diclocil® | Septic prepatellar bursitis — empirical oral antibiotic for community-acquired S. aureus

DOSE 500 mg orally every 6 hours (QID), taken on empty stomach; duration 10–14 days; adjust per culture and sensitivity results

PBS STATUS ✓ PBS: General benefit

NOTES First-line empirical oral antibiotic for septic prepatellar bursitis in community settings. Active against MSSA. Take 30 minutes before food for optimal absorption. Review at 48–72 hours — if not improving, consider IV therapy or MRSA cover. If penicillin allergy: cefalexin 500 mg QID or clindamycin 450 mg TDS.

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Flucloxacillin IV — severe septic bursitis

Flopen® | Septic bursitis — IV therapy for severe or hospital-requiring disease

DOSE 2 g IV every 6 hours; duration guided by clinical response (typically 5–10 days IV then step-down to oral); adjust for renal function

PBS STATUS ✓ PBS: General benefit (hospital supply)

NOTES For severe septic bursitis, immunocompromised patients, failure of oral therapy, or systemic sepsis. Requires hospital admission for IV administration. Step down to oral dicloxacillin when improving. If MRSA suspected (healthcare contact, prior MRSA): use vancomycin (TDM-guided dosing).

⚠️

Colchicine — crystal bursitis (gout) only

Colgout® | Acute gout-related bursitis — when NSAIDs are contraindicated

DOSE 0.5 mg orally BD–TDS; continue for 3–5 days or until flare resolves; reduce dose in renal impairment

PBS STATUS ✓ PBS: Authority required — gout

NOTES Use for gout-related bursitis when NSAIDs are contraindicated (renal impairment, cardiovascular disease). Start early in flare for best efficacy. Diarrhoea is the most common and dose-limiting side effect. Do not use as primary therapy for non-septic or septic bacterial bursitis. PBS Authority required for acute gout.

Acute Flare Management

Acute prepatellar bursitis presentations require rapid assessment to distinguish septic from non-septic disease. The management pathway diverges at this point — septic bursitis is a medical urgency requiring antibiotics, while non-septic bursitis is managed conservatively.

Key principle: Aspirate first, treat second. Aspiration provides diagnostic information and immediate symptomatic relief. Never give corticosteroid injection before culture results confirm non-septic bursitis.

Assess for septic bursitis first: Check temperature, skin integrity over bursa, onset timeline, systemic status, immunocompromise. Mark the erythema margin with a pen at first presentation to track progression. If any doubt — treat as septic until proven otherwise.
Aspirate the bursa: Using strict aseptic technique, aspirate as much fluid as possible. Send for WBC, MC&S, Gram stain, crystals. Apply compressive bandage after aspiration.
If septic bursitis confirmed or suspected: Commence empirical antibiotics immediately (dicloxacillin 500 mg QID orally if systemically well; IV flucloxacillin if severe or systemically unwell). Admit if unable to take oral therapy, immunocompromised, or no clinical improvement at 48–72 hours. Repeat aspiration every 1–3 days until resolved.
If non-septic bursitis confirmed: NSAIDs or paracetamol for pain; consider corticosteroid injection once culture result confirmed negative (48–72 hours); knee padding, activity modification, ice and compression.
For crystal bursitis: NSAIDs first-line if no contraindications; colchicine if NSAIDs contraindicated; corticosteroid injection effective. After acute flare resolves, commence urate-lowering therapy if gout confirmed and not already on treatment.
Occupational considerations: If occupational trigger identified, document and advise on knee protection (gel pads, hard-shell knee pads). Consider WorkCover referral for modified duties or compensation if work-related. Provide written advice on kneeling technique modification.

Monitoring and Review

Monitoring requirements differ between septic and non-septic prepatellar bursitis. Septic bursitis requires close review at 48–72 hours to ensure antibiotic response and guide escalation decisions.

Septic bursitis (48–72 hours)

Reassess temperature, erythema margins (compare with pen markings), swelling size, and pain. Review culture results to guide antibiotic adjustment. If not improving: escalate to IV antibiotics, re-aspirate, arrange surgical drainage consult. If improving: complete oral antibiotics for full 10–14 day course.

Non-septic bursitis (1–2 weeks)

Reassess bursal size, pain, and function. If fluid reaccumulated: re-aspirate and consider corticosteroid injection (culture confirmed negative). Review occupational exposures and compliance with knee protection. If not resolving after 4–6 weeks: surgical referral for chronic bursitis assessment.

Post-antibiotic review

Review at completion of antibiotic course. Confirm resolution of swelling, pain, and systemic features. Repeat aspiration if residual fluid present. Failure to resolve after 14 days of appropriate antibiotics warrants surgical review for bursectomy.

Recurrence prevention

For recurrent non-septic bursitis: review occupational risk factors; assess for underlying inflammatory arthropathy (gout, RA, spondyloarthritis); refer physiotherapy for ergonomic assessment. Bursectomy considered for multiple recurrences requiring repeated aspiration.

Special Populations

Specific patient groups require modified assessment and management strategies for prepatellar bursitis.

Immunocompromised Patients

Higher risk of septic bursitis and atypical organisms (gram-negative, fungal, or mycobacterial in severely immunocompromised). Lower threshold for aspiration and antibiotic therapy. Consider hospital admission for IV antibiotics. Inform the microbiology laboratory of immunosuppression status when submitting cultures. Corticosteroid injection is contraindicated until infection is excluded with certainty.

Diabetes Mellitus

Increased susceptibility to infection and impaired wound healing. Septic bursitis more common and may present with blunted inflammatory response (reduced fever). Low threshold to aspirate and treat as septic. Ensure glycaemic control during acute infection. Corticosteroid injection will temporarily raise blood glucose — warn patient, monitor BSL over 24–48 hours post-injection.

Gout Patients

Crystal bursitis from monosodium urate deposition may mimic or co-exist with septic bursitis. Always aspirate and examine for crystals. Commence urate-lowering therapy (allopurinol) after acute flare resolves if not already on treatment. Colchicine prophylaxis recommended during initiation of allopurinol. Target serum urate <0.36 mmol/L.

Occupational Bursitis

Document occupational exposure for WorkCover purposes. Advise on knee padding (gel pads, hard-shell pads), ergonomic workstation modification, and task rotation. Provide medical certificate for modified duties if required. Consider referral to occupational physician for persistent or recurrent work-related bursitis. Preventive knee pads significantly reduce recurrence in at-risk workers.

Aboriginal and Torres Strait Islander Health Considerations

Aboriginal and Torres Strait Islander peoples may present later with musculoskeletal conditions due to barriers to access, and have higher rates of comorbidities (diabetes, CKD) that modify management. Cultural safety and community-based care are essential components of effective management.

🌐 Access and Presentation

Aboriginal and Torres Strait Islander patients may present later in the course of prepatellar bursitis, including with complications such as cellulitis or early abscess. Telehealth consultations through Aboriginal Community Controlled Health Organisations (ACCHOs) are key access points. GP advocacy for timely specialist or surgical referral is important when drainage is required for septic bursitis.

🤝 Culturally Safe Assessment

Engage Aboriginal Health Workers and use a patient-centred, culturally safe approach when assessing and aspirating the bursa. Explain procedures clearly and obtain informed consent. Respect patient autonomy in treatment decisions. Discharge planning must account for home circumstances — oral antibiotic adherence may require support strategies such as blister packs, Webster-paks, or community nurse follow-up.

🏠 Comorbidity-Informed Management

Higher rates of type 2 diabetes and chronic kidney disease modify pharmacotherapy. NSAIDs are higher risk in CKD — prefer paracetamol and topical NSAIDs. Diabetes increases septic bursitis risk and impairs healing. Corticosteroid injection causes transient hyperglycaemia — ensure blood glucose monitoring. Gout rates are elevated particularly in Torres Strait Islander communities — consider uric acid testing and urate-lowering therapy in recurrent cases.

📋 Adherence and Follow-up Support

Ensure follow-up plans are realistic given transport and geography. Community nursing can support wound monitoring after aspiration or surgical drainage. Simplify antibiotic regimens where possible (BD preferred over QID where culture sensitivity allows). ACCHS care coordinators can assist with medication management and follow-up. Antibiotic completion is critical in septic bursitis to prevent treatment failure and recurrence.

Medication Stewardship

Antibiotic stewardship is a critical principle in prepatellar bursitis management. Antibiotics are indicated only for confirmed or strongly suspected septic bursitis — not for non-septic bursitis. Unnecessary antibiotic prescribing is common in bursitis and contributes to antimicrobial resistance without patient benefit.

Aspirate before antibiotics where possible: Culture-guided therapy reduces broad-spectrum antibiotic use and allows targeted de-escalation. Always obtain bursal fluid cultures before commencing antibiotics when clinically feasible. If the patient is systemically unwell, commence empirical therapy concurrently and adjust on culture results.
Do not use antibiotics for non-septic bursitis: NSAIDs, aspiration, activity modification, and compression are the correct management pathway. Antibiotic prescribing for non-septic bursitis does not benefit the patient and contributes to resistance. Document non-septic diagnosis clearly.
Target antibiotic duration: 10–14 days total (oral or IV-to-oral switch) for uncomplicated septic bursitis. Extend only if immunocompromised, slow clinical response, or abscess formation. Do not continue antibiotics beyond clinical resolution without specific indication.
Corticosteroid stewardship: Only after culture negativity confirmed. Do not inject prophylactically or for mechanical bursitis without inflammatory features. Limit to 1–2 injections per episode. Overuse predisposes to infection and bursal wall atrophy.
NSAID stewardship: Use lowest effective dose for shortest duration. Reassess need at each prescription. Monitor renal function, GI symptoms, and blood pressure in ongoing use. Add PPI for GI protection in high-risk patients or if oral NSAIDs needed for >2 weeks.

Follow-up and Prognosis

The prognosis for prepatellar bursitis is excellent with appropriate management. Non-septic bursitis typically resolves within 4–8 weeks with conservative management. Septic bursitis resolves with appropriate antibiotic therapy in the majority of cases; surgical drainage is required in a minority. Recurrence is common in those who continue occupational kneeling without protective measures.

Acute Presentation

Assess and differentiate septic vs. non-septic bursitis; aspirate if indicated; send fluid for MC&S, WBC, Gram stain, crystals; commence appropriate management; provide patient education on activity modification, knee protection, and follow-up timing; mark erythema margin if septic features suspected.

48–72 Hours (Septic)

Review temperature, erythema margin (compare with initial pen markings), swelling, and pain. Culture results guide antibiotic de-escalation or escalation. Re-aspirate if fluid reaccumulated. If deteriorating or not improving: arrange hospital admission for IV antibiotics or surgical drainage consultation.

1–2 Weeks (Non-septic)

Reassess bursal swelling. If reaccumulated: re-aspirate and consider corticosteroid injection (culture confirmed negative). Reinforce activity modification and knee protection. Review occupational risk factors and document for WorkCover if applicable.

4–8 Weeks

Most cases should be resolved. If not: reconsider diagnosis (underlying inflammatory arthritis, gout, crystal disease); surgical referral for bursectomy if chronic non-resolving bursitis; physiotherapy for knee strengthening and prevention. For recurrent bursitis: inflammatory arthritis workup and uric acid testing.

References and Guidelines

Therapeutic Guidelines — Rheumatology: Bursitis; available via eTG complete
Antibiotic Expert Groups — Therapeutic Guidelines: Antibiotic; eTG complete; Soft tissue infections: Septic bursitis
RACGP — Red Book: Musculoskeletal conditions in Australian general practice; 2022
Baumbach SF et al. — Prepatellar and olecranon bursitis: literature review and development of a treatment algorithm; Arch Orthop Trauma Surg 2014
Reilly D, Kamineni S — Olecranon bursitis; J Bone Joint Surg Br 2016 (principles applicable to prepatellar bursitis)
Perez C et al. — Septic bursitis: a study of 40 cases; J Infect 2004
Ho G Jr, Tice AD — Comparison of nonseptic and septic bursitis; Arch Intern Med 1979
Arthritis Australia — Bursitis patient information; arthritisaustralia.com.au